Formulation of personal care products containing siloxane and natural lipids（II）


Functions of siloxane and natural lipids


Siloxane and natural lipids have complementary advantages in many aspects in the production formula. Siloxane has excellent aesthetic properties, which can improve the gloss and spreading ability of the product and reduce the stickiness of the product. Volatile siloxane (such as cyclic pentameric siloxane) is an excellent spreading agent for pigments, sunscreen and anti-sweat salts. However, because of their volatility, they have only temporary moisturizing effects; natural lipids have better moisturizing properties, and their moisturizing effect is generally better than that of siloxane. Part of the reason is that they have better retention.


Natural lipids containing certain fatty acids have many health effects on skin, but siloxane does not. Polyunsaturated fatty acids, such as linoleic acid and linolenic acid, are called essential fatty acids (EFAs), because they are necessary for human health, but can not be synthesized by human body. Especially, two kinds of EFAs, alpha-linolenic acid and gamma-linolenic acid, have attracted much attention as nutrients. Triglycerides from many plants are an excellent source of these fatty acids. Among their many functions in the human body, lipids as part of skin barrier function must have EFAs. It has also been found that local use of gamma-linolenic acid-rich borage oil can help restore the skin barrier function damaged by surfactants. In addition, consumers'consumption needs for personal care products now There is a tendency to use more natural ingredients. Obviously, the use of natural lipids can meet the needs of consumers.


Siloxane and natural lipids include a number of substances with a variety of aesthetic properties, polydimethylsiloxane is the most commonly used non-volatile siloxane emollient, its aesthetic properties depend on its molecular weight. Low viscosity (low molecular weight) polydimethylsiloxane has excellent spreading property, but its skin feeling is slightly dry; with the increase of its molecular weight, its spreading property is worse and the skin feeling is less comfortable. Therefore, high molecular weight polydimethylsiloxane is often mixed with volatile siloxane (such as cyclic pentameric siloxane) to help form thin films on hair or skin. The different fatty acid composition of natural triglycerides from different sources not only determines their melting point (such as oil-fat comparison), but also determines their aesthetic properties. Natural oils rich in polyunsaturated fatty acids have a comfortable skin feel, while natural oils have a poor skin feel. By mixing natural lipids from different sources, the skin sensation of the mixture is similar to that of hydrocarbon emollients such as vaseline.


(3) Formulation Technology


The polarity of natural triglyceride lipids is much stronger than that of common siloxanes (such as polydimethylsiloxane and cyclic pentameric siloxane), which means that siloxane and natural lipids are often insoluble (mutually soluble). When siloxane and natural lipids are used together in emulsion formulations, the insolubility of these two components is less problematic than in other formulations, such as transparent or anhydrous rod formulations. As long as the emulsifying system is adequate for the coexistence of these two emulsifiers, the insolubility of siloxane and natural lipid components is not a problem. In fact, this lack of mutual solubility can also increase the aesthetic effect of each emollient. In production, the insoluble components of the oil phase in the formulation keep some form of mixing in the oil phase mixing tank. So that different oil phase components can be evenly added to the batch, which is usually an ideal state of great need. In formulations, the solubility of emollients is important, and it is practical to know which siloxane is soluble in different natural lipids. Generally speaking, in siloxane, the solubility of natural oils is better than that of natural oils, and some siloxanes are better than other lipids in solubility.


From Cosmetics Science